Comparative Evaluation of Surface Roughness of Different Rotary Nickel-Titanium (NiTi) Files After Autoclaving: An Atomic Force Microscopic Study

Abstract

Canal preparation is a critical step in endodontic therapy. Introducing nickel-titanium (NiTi) rotary instruments has significantly reduced the likelihood of errors in curved canals. However, due to their price, these instruments are often reused following autoclaving. The aim of this study is to compare and evaluate the surface characteristics of two designs of rotary NiTi files used in curved canals and subjected to multiple autoclaving cycles, utilizing an atomic force microscope for detailed analysis. MethodsA total sample size of 24 files was taken, 12 files of Hyflex EDM (Coltene/Whaledent, Germany) files and WaveOne Gold (Dentsply Sirona, USA) files were then divided into four groups (n=6) as follows: Group I: Hyflex EDM control group; Group II: WaveOne Gold control group; Group III: Hyflex EDM experimental group; Group IV: WaveOne Gold experimental group.Sterilization using an autoclave was performed thrice for Groups I and II files. The files in Groups III and IV were used in simulated curved canals three times and autoclaved after each use. Atomic force microscopy was used to assess the surface roughness of the files after the first and third autoclave cycles. ResultsThe results showed that, without statistical significance, Hyflex EDM exhibited the highest surface roughness after the first usage among the two file systems. ConclusionIt can be concluded that both Hyflex EDM and WaveOne Gold files produced similar levels of surface changes when subjected to multiple usage and autoclaving cycles.